From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E03F1C282CA for ; Wed, 13 Feb 2019 18:33:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B57422086C for ; Wed, 13 Feb 2019 18:33:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HUaXNF7P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387577AbfBMSd3 (ORCPT ); Wed, 13 Feb 2019 13:33:29 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:54218 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726940AbfBMSd3 (ORCPT ); Wed, 13 Feb 2019 13:33:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=2+DpYQ1RgGmMz3i+2Oak2qboDEh+xxduT0QJZ3VtomY=; b=HUaXNF7P0vNTbCRTBTt4MZvWi oaNnNwx1FlJT43/Jt+uZJOe+ATtf9fqO8yw5rN6azk1+k6CKAPLGk423nL+bQOmXXEFYuQvGojxhE e+PRZsoU+NagWzm51En666YIEo4Pk5qMW7Y47AzOHOVpdTi34TUSJaFxjkXsvPlyuuJR123i3KVc8 +itdTS5Qza6pOBQcKCSwPPyXnhLXnnbHLDPaOpTq8EzPAdnnFcEVUiGgGkdSxNeK9RUTgaUrpEkt/ 0EHm4w6kYGEwCL+J7Dmw/jnERj+THqTC6t1AzE996p2bvPWVb0Pd842XXDmAo2fk+6WtsvTkgrizZ KiKVIj7/A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtzLR-0005jN-1w; Wed, 13 Feb 2019 18:33:17 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 45EF0202CEF76; Wed, 13 Feb 2019 19:33:14 +0100 (CET) Date: Wed, 13 Feb 2019 19:33:14 +0100 From: Peter Zijlstra To: Linus Torvalds Cc: Will Deacon , linux-arch , Linux List Kernel Mailing , "Paul E. McKenney" , Benjamin Herrenschmidt , Arnd Bergmann , Andrea Parri , Daniel Lustig , David Howells , Alan Stern , Tony Luck Subject: Re: [RFC PATCH] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section Message-ID: <20190213183314.GB32494@hirez.programming.kicks-ass.net> References: <20190211172948.3322-1-will.deacon@arm.com> <20190213172047.GH6346@brain-police> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 13, 2019 at 10:27:09AM -0800, Linus Torvalds wrote: > Yeah, yeah, there's the SGI "SN" platform that apparently has a bug, > so because of that platform problem maybe it needs the more complex > "use a flag" model. But even the complex model isn't _hugely_ > complex. > > But we *could* first just do the mmiowb() unconditionally in the ia64 > unlocking code, and then see if anybody notices? > > Tony, comments? Are there any SGI SN machines around any more? I think the last time this came up, it was said that those people still running Linux on Itanium were running old disto kernels, not upstream. So yeah, we could probably do whatever and nobody would ever notice, except maybe Al, who is rumoured to still have an ia64 :-)